1. Field of the Invention
The present apparatus relates to a measuring method of sedimentation rate of sediments in a liquid sample, and its apparatus, and more particularly to the technology for measuring optically the sedimentation rate of sediments in a liquid sample contained in a test tube or other transparent container.
2. Description of the Related Art
A typical example of measurement of sedimentation rate of sediments in a liquid sample is measurement of sedimentation rate of erythrocytes which is one of the most common clinical examinations. As the measuring method of erythrocyte sedimentation rate, the Westergren method is employed as a standard technique. In the Westergren method, a specific blood sampling tube held in vertical position is filled with nonclotting blood and let stand, and the height of the blood cell layer caused by sedimentation of erythrocytes (sedimentation height of erythrocytes) is recorded by a laboratory technician in one hour after letting stand, then the speed of sedimentation of erythrocytes is judged.
In this measuring method, however, it takes at least one hour from start till end of measurement, and it is not suited in case of emergency.
The blood sampling tube used as a test container in the Westergren method is a glass tube of 2.55 mm in inside diameter, and 300 mm in overall length, and to fill this blood sampling tube with 1 part of sodium citrate solution as coagulant and 4 parts of blood by volume, about 2 cc of blood is needed, and it is not suited to hematological examination of infants essentially small in the allowable blood sampling volume.
It is hence an object of the invention to present a novel technology for measuring the sedimentation rate by solving the problems of the prior art.
It is other object of the invention to present a measuring method of sedimentation rate capable of measuring the sedimentation rate of liquid sample containing sediments accommodated in a test container, accurately in a short time, even if the sample is a small amount of liquid, by using optical means.
It is another object of the invention to present a measuring apparatus of sedimentation rate for executing this measuring method.
The measuring method of sedimentation rate of the invention comprises the steps of holding a test container accommodating a liquid sample containing sediments at a specified inclination angle so as to produce a natural convection to promote sedimentation of the sediments in the liquid sample, projecting light to the test container, detecting the light passing through the test container electrically, and calculating the depth of supernatant in the liquid sample from the time-course changes of this detected value so as to measure the sedimentation rate of the sediments.
A first constitution of the measuring apparatus of sedimentation rate of the invention comprises inclination holding means for holding a test container accommodating a liquid sample containing sediments in an inclined state, projecting means for projecting light to the test container, photo detecting means disposed oppositely to the projecting means across the test container, for detecting the light passing through the test container from the projecting means, and converting photoelectrically, light quantity change measuring means for measuring time-course changes of the photo detecting means output, and sedimentation rate calculating means for calculating the sedimentation rate of sediments in the test container on the basis of the result of measurement by the light quantity change measuring means.
A second constitution of the measuring apparatus of sedimentation rate of the invention comprises a plurality of inclination holding means for holding a plurality of test containers accommodating liquid samples containing sediments in an inclined state, a turntable on which the plurality of inclination holding means are disposed on the circumference, being supported rotatably about its central axial line, rotation driving means for rotating and driving this turntable, for indexing and stopping one of the test containers so as to be positioned at the measuring position, projecting means for projecting light to the test container positioned at the measuring position, photo detecting means disposed oppositely to the projecting means across this test container, for detecting the light passing through the test container from the projecting means, and converting photoelectrically, light quantity change measuring means for measuring time-course changes of the photo detecting means output, control means for controlling this light quantity change measuring means and the rotation driving means in synchronism, and sedimentation rate calculating means for calculating the sedimentation rate of sediments in the test container on the basis of the result of measurement by the light quantity change measuring means.
Preferably, the inclination holding means is, for example, for use in measurement of sedimentation rate of erythrocytes, designed to incline and hold two kinds of test containers, that is, standard test container (standard tube) and fine test container (capillary tube), and includes detecting means for detecting which one of the two test containers has been inserted.
As in the invention, when the test container filled with liquid sample containing sediments is held in an inclined state, the sedimentation rate of the sediments is promoted by natural convection. By sedimentation of the sediments, a boundary of supernatant and sediments appears in the test container, and this boundary descends with the passing of the time, and descent of the boundary stops at a certain time (sedimentation of sediments stops).
The quantity of light passing through this liquid sample changes with the clarity (corresponding to the content) of the test container (transparent container), and the light passing through the space above the supernatant (space free from liquid sample), the light passing through the supernatant, and the light passing through the sediments can be clearly distinguished. Hence, by detecting the change of the transmitted light quantity, the liquid level of the supernatant, and the boundary of the supernatant and sediments can be securely discriminated.
Therefore, by detecting the changes of quantity of light passing through the test container electrically by means of CCD the line sensor, photo diode array, CCD area sensor, or other photo detectors, the depth of the supernatant is calculated from the time-course changes of these detected values. As a result, from the calculated value and the measuring time, the sedimentation rate of sediments can be calculated.
For example, when measuring the sedimentation rate of erythrocytes by using a mixed solution of 1 part of sodium citrate solution and 4 parts of blood by volume, the quantity of light changes significantly when passing through the boundary of sediments or blood cell layer (clotting sediments of erythrocytes and other corpuscles) and supernatant or plasma, and the boundary of the plasma and space free from mixed solution, that is, the liquid level of plasma, and by detecting this change of quantity of light by CCD line sensor, photo diode array, CCD area sensor or the like, the time-course changes of plasma depth can be detected in real time, and the maximum depth can be calculated, so that the sedimentation rate of erythrocytes can be determined.
In this measurement of sedimentation rate of erythrocytes, by holding the test container in an inclined state, the sedimentation rate of erythrocytes is promoted by natural convection, and the sedimentation rate of erythrocytes can be measured in a short time.
This promoting effect of sedimentation rate of erythrocytes by holding the test container in an inclined state is the same if the test container is a fine tube (capillary tube), and therefore in babies and infants small in the allowable blood sampling volume, the sedimentation rate of erythrocytes can be measured safely, promptly, and accurately.
These and other objects and features of the invention will be better understood and appreciated from reading of the detailed description together with the accompanying drawings and novel facts disclosed in the claims.